If Team Rocket turns Ash into a Pokemon, it could lead to a really interesting story. Ash would have to experience the world from a Pokemon's perspective. He'd understand their struggles, like being caught and trained. This could also be a way for him to better understand his own Pokemon and their bond with him. And it would be a wild adventure as he tries to find a way to turn back to his human form.
In a fanfiction where Ash joins Team Rocket, it could lead to some really interesting storylines. Ash has a lot of knowledge about Pokémon training that Team Rocket lacks. He could potentially teach them new techniques, but at the same time, his moral compass would be constantly at odds with their devious ways. Maybe he joins them because he's somehow tricked or he has his own secret plan to take them down from the inside. It would be a great opportunity to explore different aspects of his character and how he adapts to this new situation.
The plot could involve Ash going on a journey to find and rescue his Pokémon. He might encounter new allies along the way who also have a vendetta against Team Rocket.
He was probably devastated. Ash had such a strong bond with his Pokémon. Losing them would be like losing part of himself. He might have initially been in shock, unable to believe what had happened.
Pikachu would probably be very confused at first. It's used to fighting against Team Rocket, not being on their side. It might resist and try to zap Ash to snap him out of it.
Some of his more loyal Pokemon might try to resist the change. For example, Pikachu could use electric shocks to try and jolt Ash back to his senses. Pikachu has a strong bond with Ash and would be very confused and sad about his decision to join Team Rocket.
Yes, in some Team Rocket fanfictions, Ash can be depicted in various ways that might involve him having some sort of connection to Pokémon in a different light. Maybe he could be experimented on by Team Rocket to gain Pokémon - like abilities, or be transformed into a Pokémon - like being in a very creative and out - of - the - box fanfiction concept.
If Team Rocket turns Ash into a Pokemon, his relationship with his old Pokemon would change. His Pokemon might not recognize him at first. But as they sense his familiar spirit, they could try to protect him. And Ash, in his new form, could learn a lot about the true nature of Pokemon. He could discover secrets about their evolution, abilities, and the hidden powers within them that he never knew as a human trainer.
One thing that would happen is that his Pokémon battles would take on a whole new meaning. Instead of battling for the sake of becoming a Pokémon master, he might be battling to further Team Rocket's goals. His Pokémon would have to adjust to this new purpose. Also, Ash would probably have to wear Team Rocket's uniform, which would be a really strange sight for fans who are used to seeing him in his normal get - up.
One interesting storyline could be Team Rocket actually helping Ash in a dire situation. Maybe they realize that a greater evil is about to destroy the Pokemon world and they decide to team up with Ash for once. Their skills in stealing and sneaking around could be useful in gathering information about this new threat.